Neck Tension issues? (different seating CBTO measurements)

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Neck Tension issues? (different seating CBTO measurements)

Post by cirles » 11 May 2019, 4:21 pm

New to reloading, so this is where I have progressed to so far with new brass. Will multiple re seating of a case (dummy(s) in this situation), in other words incrementally pushing down the projectile to desired measurement (CBTO), stuff the neck tension up so that you get different measurements from other cases which had been subjected to the same thing (long story) from a Seating Die? Will not lubricating inside or outside of the case neck cause this issue? All 4 dummys cases have width measurements of the neck after seating within 6/10 thousandths (0.0006) of an inch (micrometer measurements), so seem to be within margins. CBTO measurements vary up to 10 thousandths (0.0100) of an inch difference (2.2510, 2.2545, 2.2610, 2.2615 inches). Press is Forster Co-Ax.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by Stix » 11 May 2019, 6:18 pm

G'day circles...
Maybe its just me (ive been told i cant read), but im struggling to understand your question, or questions...ive read it over many times & keep having to go backwards to try & understand..
Not having a go, but maybe try & word it from the perspective of the reader not knowing what youre on about.

Aside from that, from what i can guess youre asking, id say no, lubing necks wont "cause" neck tension changes, assuming youre lubing all necks the same.
I wouldnt slowly adjust each & every bullet down incrementally, not unless i had a serious OCD or some kind of Autism type disease anyway.

When i seat, ill slowly adjust the die down intill i get close to my desired length, but before i get all the way there i seat a diff bullet or 2 in diff cases & check that. Then wind down die to desired length, then seat the rest, checking every 5-10 for consistant length to ogive.
Also, these first bullets i seat are usually in the cases i have to the side of my batch--either the lightest or heaviest, then ill seat the rest...that way those cases are more likely to be used as sighters or fowlers, so any slight differences they have will not be noticable-having said that i just hunt with factory rifles & cheap bullets-so its all mute for me anyway-i just do it cos im afflicted with a bit of OCD.

If youre refering to the difference in ogive measurements from loaded round to another, it could be the projectiles--i have some projectiles that vary a lot, & depending on the seater die im using, i can still get up to .0008" between rounds in any batch.
So the seater die along with actual ogive dimensions of the given bullet can potentially make a difference that big.

Also, what is CBTO...?...the only thing i can guess is "case base to ogive"...anyway, if thats not you mean, i have no idea what youre asking.... :unknown:

Hope that helps a bit...
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Re: Neck Tension issues? (different seating CBTO measurement

Post by Member-Deleted » 11 May 2019, 6:39 pm

Good day Cirles mate if you've pushed a projectile in and out of a dummy brass a few times then the neck tension may change and the oal length of fresh projectile seating in new shell may differ if you are getting different lengths in lengths I would check that the seating die was tight and all else is firm and if you are seating ballistic tips check that the tips aren't hitting the inside of the adjustment screw sometimes the tips are too long mine was hitting so I drilled mine out I was having the same problem getting differing lengths and I was pointed in the direction of the adjustment screw hope this may help :thumbsup:
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Re: Neck Tension issues? (different seating CBTO measurement

Post by cirles » 11 May 2019, 7:23 pm

Hi Stix,
Thanks for the input, & without writing a manifesto I tried to condense things as much as possible & obviously made assumptions about what people would know about what I am doing. Really appreciate you taking the time to reply & pointing out this is not making sense. I hope the following makes more sense of what I am trying to explain.
I am totally new to reloading & shooting, so have never done this before. I had finally found where my “Lands” measurements are for my 6.5 Creedmoor rifle (2.2715 inches [Case Base to Ogive] CBTO, so am at the stage of loading my very 1st ammunition (brand new cases & projectiles/bullets not used in the rifle previously). So, was making up a dummy round to be 0.0200 inches shorter (to act as a future reference for setting up the seating die for all other new same brass & just generally a reference), BUT had mistakenly actually made them 0.0200 inches longer (2.2915) inches, & when trying to reach this desired measurement kept under sizing them, thus the 1st 3 attempts at dummy rounds. When I was trying to reach the measurement for each of these dummy cases I was only incrementally pushing/reseating them a small measurement at a time as I could not work out with my die how much movement per revolution of the seating stem would change the measurement, so was being overly cautious in doing this a bit at a time as I didn’t think it would have a detrimental effect. Now after realising my measurement for all 3 dummy rounds was too long anyway, on the final dummy case (4th) I corrected this to the 2.2515 inches needed and performed the sizing in the same way as previously, bit by bit. Chambered that round to make sure it would fit, & since all the other incorrect cases where all longer than the 2,2515 inches measurement, decided to run them through the die as well to see if I get a uniform result, which obviously I did not, so therefore the question(s).

To clear up the lube question, I lubed only 1 dummy round, the rest I did none at all

I have finally worked out how to calculate the stem size movement (needed to read the instructions more carefully) to avoid having to seat multiple times in the future but am still puzzled why I am getting these different CBTO measurements for seating on the 3 other dummy cases. My reference to the Neck Width measurements was to show that they are all as they should be, but even so has the neck tension been altered to such an extent buy the multiple seating for each dummy case & this is causing the size difference, which for 2 rounds is huge I believe.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by cirles » 11 May 2019, 7:34 pm

Forgot to include how I arrived at the neck tension needed -

Neck Tension – 6.5 Creedmoor projectile width (0.264) + Neck thickness of case (0.014 x 2 = 0.028) = 0.292, so Neck width to achieve 2 thousandths neck tension when seating would be 0.290 which is what brand new lapua brass measures, so no need to size.

I had measured multiple Berger projectile width's & they all essentially came to 0.264 inches, same with the Lapua Brass neck width.

Hopefully my reasoning above is correct for what I am doing :D

Also lightly champered inside & outside case mouths of brass.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by TassieTiger » 11 May 2019, 9:18 pm

Mate a I’m finding very similar things with my press and it is doing my head in.
I expect that once a seating die is locked off, if the case length is exactly the same then the case base to ogive should be exactly the same each time - but I’m getting variances beyond what I’d expect - certainly beyond the 20 thousandth one would use as a starting point from lands.
I’ve actually found that the turret press I use, has a few mm of movement up/down/left/right depending on which way I swing on the handle and I think this is where my issue lies - I’d pay close attention to your mounting, your press, your die...etc.
I’ve noticed that if my shell holder sits in one direction vs 90degs - I get a different reading as well...
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Re: Neck Tension issues? (different seating CBTO measurement

Post by SCJ429 » 11 May 2019, 9:50 pm

If you are loading for competition you can load to jam +20 thou. This ensures all bullets are jammed even of the ogive lenght varies slightly. Don't do this for hunting rounds as you can leave a bullet stuck in the lands if you remove an unfired round.

New or tumbled clean brass is very grippy, I lube the inside neck with graphite to reduce the grip. The carbon from a fired case will do this job for you.

I deliberately only partially seat a bullet and the turn the case in the die before seating it the rest of the way. I am trying to minimise runout by doing this. I have not seen any changes brought by inconsistent neck tension by doing this.

If you really want to try to have consistant neck tension you should neck turn. Even Lapua cases will benefit from this.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by Sergeant Hartman » 11 May 2019, 10:02 pm

How are u measuring the total length. With a vernier to the point/tip of the projectile (coal) or with a hornady bullet comparitor or similar which measures the ogive.

The tip measurement can change even for same bullet.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by trekin » 12 May 2019, 7:12 am

Outside the box here, but first off I would be checking the documemntation that came with whatever you are using to messure, I'm assuming a vernier callipers, for the +/- tolerances. Most digital/cheaper ones have a +/- 0.010 tolerance.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by Madang185 » 12 May 2019, 9:08 am

You might find that there is a length difference between the base of a projectile and the ogive. I have measured up to .005 difference between commercial boat-tailed projectiles. Flat based projectile are in my experience more predictable and a good batch will be within .001 of each other.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by cirles » 12 May 2019, 10:41 am

Still a bit of a mystery as was only pushing the bullet in bit by bit, not pulling it out then pushing it back in. Good idea of checking the die & have done so. It appears to be fine, Lock nut on the seating stem was tightened down, I had screwed the body down onto the sleeve section of the die as far as could go ( so locked in - this is a mircrometer seating die) & had adjusted the die as per instructions for fitting into the press & the Die lock Ring was screwed in tight as well. Bullets I am using are Berger VLD so no soft tips.
The adjustment screw (bullet seating stem?) potential issue is an interesting one, will have to keep that in mind if I cannot resolve this so thanks for indicating that.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by cirles » 12 May 2019, 10:52 am

TassieTiger wrote:Mate a I’m finding very similar things with my press and it is doing my head in.
I expect that once a seating die is locked off, if the case length is exactly the same then the case base to ogive should be exactly the same each time - but I’m getting variances beyond what I’d expect - certainly beyond the 20 thousandth one would use as a starting point from lands.
I’ve actually found that the turret press I use, has a few mm of movement up/down/left/right depending on which way I swing on the handle and I think this is where my issue lies - I’d pay close attention to your mounting, your press, your die...etc.
I’ve noticed that if my shell holder sits in one direction vs 90degs - I get a different reading as well...

Hi Tassie Tiger,
Yeah that's what is so puzzling, I expect any same cartridge & bullet placed through a set up die to come out exactly the same. I had a look at the press as suggested & can't see anything obvious in the way of excessive movement. This is the Forster Co-Ax press, so operates a bit different to the usual press in that the die 'floats' somewhat (has movement) where it is placed (thats all fine & done to instructions) plus the seating jaws area (shell holding area) is set up as per instructions as well (Forster confirmed what jaws I was supposed to use with 6.5 Creedmoor ammo) has the required 'float' as well. Still will need to spend more time looking at the press I guess & see if I can spot anything.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by cirles » 12 May 2019, 11:00 am

SCJ429 wrote:If you are loading for competition you can load to jam +20 thou. This ensures all bullets are jammed even of the ogive lenght varies slightly. Don't do this for hunting rounds as you can leave a bullet stuck in the lands if you remove an unfired round.

New or tumbled clean brass is very grippy, I lube the inside neck with graphite to reduce the grip. The carbon from a fired case will do this job for you.

I deliberately only partially seat a bullet and the turn the case in the die before seating it the rest of the way. I am trying to minimise runout by doing this. I have not seen any changes brought by inconsistent neck tension by doing this.

If you really want to try to have consistant neck tension you should neck turn. Even Lapua cases will benefit from this.

Hi SCJ429,
Not loading for competition, just want to get as much accuracy without going to the extremes of neck turning, volume & bullet weighing/sorting etc.
Not quite understanding the partial seat method you are describing here. Not 100% sure but remember some people who seat the bullet, then withdraw & move the bullet 90 or 180 degrees & then seat in again to help any potential uneven seating issue.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by cirles » 12 May 2019, 11:15 am

Ziad wrote:How are u measuring the total length. With a vernier to the point/tip of the projectile (coal) or with a hornady bullet comparitor or similar which measures the ogive.

The tip measurement can change even for same bullet.

Hi Ziad,

Use a comparitor (Forster, but thinking the Hornady may have been the better choice) for measuring the case base to ogive (CBTO) as this seems a more accurate way to measure the aspect of the bullet that is most important (measurement from the lands - unless you are looking for something that must fit the rifles magazine). I will admit though that using the vernier caliper is something of an acquired skill because it is so easy (from my experience) to measure it wrong. Because you are trying to place/balance the base of the case on a relatively narrow blade of the vernier it is easy to orientate this wrong & get a incorrect measurement. I place quite a firm pressure on the vernier & wiggle the bullet around backwards & forwards & side to side (90 degress) on that blade after making sure it is centralized, but always wonder if I am using too much pressure.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by cirles » 12 May 2019, 11:29 am

trekin wrote:Outside the box here, but first off I would be checking the documemntation that came with whatever you are using to messure, I'm assuming a vernier callipers, for the +/- tolerances. Most digital/cheaper ones have a +/- 0.010 tolerance.

Hi trekin,

Am using a Mitutoyo Absolute Digimatic vernier, so accuracy should be good. That saying, the operator has a lot to play in that & in my previous repy to Ziad, I must admit to finding using it not the easest thing to do, but am confident enough to know I am consistent in how I use it (have measured a lot of related reloading stuff, from lands measurements (Hornday OAL Gauge - took me some time to work out how to use this correctly as was getting inconsistent measurements), to all sorts of case measurements for new brass & purchased bullets).
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Re: Neck Tension issues? (different seating CBTO measurement

Post by cirles » 12 May 2019, 11:38 am

Madang185 wrote:You might find that there is a length difference between the base of a projectile and the ogive. I have measured up to .005 difference between commercial boat-tailed projectiles. Flat based projectile are in my experience more predictable and a good batch will be within .001 of each other.

Hi Madang185,
Thats a good idea, thought about this yesterday but since I am using Berger VLD Target this should not be an issue but will do so just to put my mind at ease. The thing is I was getting a 0.010 + difference on 2 of those dummy rounds & as you showed here your differences did not come anywhere near that
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Re: Neck Tension issues? (different seating CBTO measurement

Post by SCJ429 » 12 May 2019, 12:16 pm

My experience with Berger bullets is that they are so good that batching them is not needed. When I use Sierra MK, then batching is beneficial.

I have found flat based bullets have an advantage out to 300 metres, for 500 and beyond the boat tail design with its better BC is the best choice.

What are you using your Creedmoor for?
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Re: Neck Tension issues? (different seating CBTO measurement

Post by cirles » 12 May 2019, 12:38 pm

SCJ429 wrote:My experience with Berger bullets is that they are so good that batching them is not needed. When I use Sierra MK, then batching is beneficial.

I have found flat based bullets have an advantage out to 300 metres, for 500 and beyond the boat tail design with its better BC is the best choice.

What are you using your Creedmoor for?



Will be getting into fly shooting (500 meters) some stage into the future but have a goal of shooting water jugs (4 litres) measuring 9 inches by 6 inches at 1000 meters (still havn't worked out what type of moa my rifle will require for that :D ). Rifle is a Tikka TAC, needed a pistol type grip rifle as have a dodgy right arm courtesy of a motor vehicle accident.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by Apollo » 12 May 2019, 1:24 pm

Just a few points I have picked up and not sure what you are doing or using.

The Bullet Seating Die - Does it have a seating insert designed for seating VLD Bullets (Secant Ogive) or is it the standard Tangent Ogive type that just maybe allowing the bullet meplat to touch the bottom of the seating stem rather than use the ogive.

You could try using one of these on your Calipres to give you a greater footprint for measuring.
http://brtshooterssupply.com.au/product ... -base.html

Unless you have a specific Wall Thickness Micrometer like one of these you are not going to get accurate measurements of case wall thickness. The blade of a calipre isn't going to give you very accurate readings, especially the further into the case neck you try and measure.
http://brtshooterssupply.com.au/product ... 1inch.html

Measuring bullet diameters you really need to be using a very accurate micrometer and take one measurement on the bearing surface of the bullet then another near the base of the bullet at the pressure ring which should be a greater measurement. I use one of these...
http://brtshooterssupply.com.au/product ... 1inch.html

This is all getting very expensive and really only to be considered if you are doing competition precision target shooting or you have plenty of money and just like getting things as exact as possible.

If you are seating, removing and re-seating a bullet in the same case you are going to reduce neck tension as every time you seat a bullet you are expanding the case neck ever so slightly unless you size the case neck every time and each time you do that you are hardening the case neck ever so slightly hence producing a slight amount of spring back compared to a case that has not been touched.

In my view every new (unfired) case should be full length resized to make sure they are all the same, then have a mandrel run down the case neck to expand evenly all cases and then have the neck sized to try and create an even set of cases. In my case I anneal every case every reload using an induction annealer set to give the best annealing I can achieve.

I have measured hundreds of Lapua cases and using the measuring equipment listed above I'll tell you that they are not all the same dimensions even over the same box batch lot. They all have differences and also hence why I skim turn case necks even if the chamber size doesn't require neck turning. Also, you really don't want to get into measuring neck thickness until the case has been fireformed and even fired at least twice as the neck material is still moving around the neck diameter.

If you want to be playing with getting bullet seating correct with being exact say 0.020" off the lands then you need a better measuring system for CBTO measurements like a dedicated measuring case and the appropriate guage to measure it like...
http://brtshooterssupply.com.au/product ... aight.html

Unless you are shooting precision target competition I wouldn't really worry about your 0.010" difference you are getting as long as your loaded rounds fit your magazine and bullets are off the lands so your setting of 0.020" gives you that safety margin. If you want to chase the best accuracy the you may want to consider single shot loading rounds that are say jammed 0.020" to jumped quite some distance say 0.100" or more then that will tell you where that bullet likes to be seated in your rifle. Who knows, it may be some jump away from the lands.

One thing I see you mentioned that you don't understand is the partial seating of a bullet. That means that you don't seat the bullet all the way into the neck in one go, say 50% then rotate the case/bullet say 90 degrees and seat the rest of the way.

I don't use the type of press you are using. All my precision reloading is done with In-Line Dies and an Arbor Press.

Hope all this helps a little with your reloading.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by Apollo » 12 May 2019, 1:32 pm

BTW...

My main precision target shooting is 500 Metre Fly of which I'm hoping to get to the Nationals next month. I don't shoot a Creedmore but something close being a 6.5x47 Lapua of which I have 3 custom built rifles and shoot both Light and Heavy Gun Class. If I'm on song and can concentrate I aim to be in the top few competitors but I'm getting older quick and the eyes/reflexes/ etc are wearing out.

It's an expensive hobby this 500 Metre Fly when you start chasing the top spots.

Hope you enjoy it.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by marksman » 12 May 2019, 1:41 pm

cirles wrote:New to reloading, so this is where I have progressed to so far with new brass. Will multiple re seating of a case (dummy(s) in this situation), in other words incrementally pushing down the projectile to desired measurement (CBTO), stuff the neck tension up so that you get different measurements from other cases which had been subjected to the same thing (long story) from a Seating Die? Will not lubricating inside or outside of the case neck cause this issue? All 4 dummys cases have width measurements of the neck after seating within 6/10 thousandths (0.0006) of an inch (micrometer measurements), so seem to be within margins. CBTO measurements vary up to 10 thousandths (0.0100) of an inch difference (2.2510, 2.2545, 2.2610, 2.2615 inches). Press is Forster Co-Ax.


without reading all posts IMO yes
in practice I have found that different neck tensions will cause different measurements

think about it if a bullet is harder to seat it will and does not seat to the same oal as one that slips in easy, the harder to seat projectile will leave a ring impression on the ogive, the difference may be a couple of thou, powder compression can make a difference as well
I have a force dial on my press that shows differing forces used to seat bullets in different cases that shows the different neck tension and oal
you have to understand that sizing brass or seating and pulling bullets can make the brass harder although when pulling a bullet you will make the neck looser as it has been stretched to the size of the bullet that had been seated
and when try to get your oal on a dummy by making small adjustments to the die will get that oal right but the next one you try at that setting will usually be different but only just so most people will make a dummy and use it for setting up the die but give a quarter turn more before seating

if you are seating close to the lands you will need consistency but if you jam or jump you wont have to be so uniform
you must also consider that bullet ogives do vary so it is beneficial to check and batch bullets for consistent oal's

I hope this helps :drinks:
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Re: Neck Tension issues? (different seating CBTO measurement

Post by cirles » 12 May 2019, 3:02 pm

Apollo wrote:Just a few points I have picked up and not sure what you are doing or using.

The Bullet Seating Die - Does it have a seating insert designed for seating VLD Bullets (Secant Ogive) or is it the standard Tangent Ogive type that just maybe allowing the bullet meplat to touch the bottom of the seating stem rather than use the ogive.

You could try using one of these on your Calipres to give you a greater footprint for measuring.
http://brtshooterssupply.com.au/product ... -base.html

Unless you have a specific Wall Thickness Micrometer like one of these you are not going to get accurate measurements of case wall thickness. The blade of a calipre isn't going to give you very accurate readings, especially the further into the case neck you try and measure.
http://brtshooterssupply.com.au/product ... 1inch.html

Measuring bullet diameters you really need to be using a very accurate micrometer and take one measurement on the bearing surface of the bullet then another near the base of the bullet at the pressure ring which should be a greater measurement. I use one of these...
http://brtshooterssupply.com.au/product ... 1inch.html

This is all getting very expensive and really only to be considered if you are doing competition precision target shooting or you have plenty of money and just like getting things as exact as possible.

If you are seating, removing and re-seating a bullet in the same case you are going to reduce neck tension as every time you seat a bullet you are expanding the case neck ever so slightly unless you size the case neck every time and each time you do that you are hardening the case neck ever so slightly hence producing a slight amount of spring back compared to a case that has not been touched.

In my view every new (unfired) case should be full length resized to make sure they are all the same, then have a mandrel run down the case neck to expand evenly all cases and then have the neck sized to try and create an even set of cases. In my case I anneal every case every reload using an induction annealer set to give the best annealing I can achieve.

I have measured hundreds of Lapua cases and using the measuring equipment listed above I'll tell you that they are not all the same dimensions even over the same box batch lot. They all have differences and also hence why I skim turn case necks even if the chamber size doesn't require neck turning. Also, you really don't want to get into measuring neck thickness until the case has been fireformed and even fired at least twice as the neck material is still moving around the neck diameter.

If you want to be playing with getting bullet seating correct with being exact say 0.020" off the lands then you need a better measuring system for CBTO measurements like a dedicated measuring case and the appropriate guage to measure it like...
http://brtshooterssupply.com.au/product ... aight.html

Unless you are shooting precision target competition I wouldn't really worry about your 0.010" difference you are getting as long as your loaded rounds fit your magazine and bullets are off the lands so your setting of 0.020" gives you that safety margin. If you want to chase the best accuracy the you may want to consider single shot loading rounds that are say jammed 0.020" to jumped quite some distance say 0.100" or more then that will tell you where that bullet likes to be seated in your rifle. Who knows, it may be some jump away from the lands.

One thing I see you mentioned that you don't understand is the partial seating of a bullet. That means that you don't seat the bullet all the way into the neck in one go, say 50% then rotate the case/bullet say 90 degrees and seat the rest of the way.

I don't use the type of press you are using. All my precision reloading is done with In-Line Dies and an Arbor Press.

Hope all this helps a little with your reloading.


Hi Apollo,
Thanks for the input. I have just purchased the the Hornady Anvil you indicated as thought this may be a solution to making vernier measurements easier to take. I have the same micrometer you indicated here as well but managed to get it much cheaper somewhere else. Did not want to go to the expense of the wall thickness micrometer as not interested in neck turning, but was informed of it for the Lapua cases I use by the person purchased from, same people you have referenced here, BRT of Queensland (as with most of my equipment so far). I understand that all cases may not have this thickness, or be concentric in that thickness but the micrometer measurements I took for those 4 cases were within 0.0006, so seem to be fine.

I am not after competition shooting type lengths/methods for accuracy, just as much as I can with equipment I currently have. So not neck turning, concentricity setups, weighing of cases, bullets, volumes etc for me. Just the dies I have..

Seating Die is the Forster 'Ultra Micrometer Seater Die' Do not have a clue what type this is regarding ogive shapes but another person in this thread did mention this (seating stem/adjustment screw interfering with the bullet tip) as a possible reason, so thanks for reaffirming this. You wouldn't happen to know would you (using Berger VLD Target 140 grain).

Just some clarification regarding the seating aspect you wrote, when you say '... removing and re-seating a bullet in the same case you are going to reduce neck tension...' do you mean the actual projectile (bullet) is removed from the case & then re seated again or simply the act of seating the bullet, then open press up & adjust measurement on the die again incrementally (a small amount), and then close press again to re seat? In other words I was just pushing the bullet in a little bit further every time (multiple times) until I reached the desired measurement wanted (would only do this for a dummy round so I had a reference for setting up the die next time for the same situation - have 300 Lapua cases).

Thanks for all the other input regarding issues to look into regarding getting accuracy, sounds like you do competition shooting & to compete at that level all the things you have listed here are what people are doing. For me, even in the 500 meter fly shoot, I am not there to compete at the top level so much as have a good time but also extract as much accuracy as possible from the rifle without going to the extremes of the competition guys.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by cirles » 12 May 2019, 3:22 pm

marksman wrote:
cirles wrote:New to reloading, so this is where I have progressed to so far with new brass. Will multiple re seating of a case (dummy(s) in this situation), in other words incrementally pushing down the projectile to desired measurement (CBTO), stuff the neck tension up so that you get different measurements from other cases which had been subjected to the same thing (long story) from a Seating Die? Will not lubricating inside or outside of the case neck cause this issue? All 4 dummys cases have width measurements of the neck after seating within 6/10 thousandths (0.0006) of an inch (micrometer measurements), so seem to be within margins. CBTO measurements vary up to 10 thousandths (0.0100) of an inch difference (2.2510, 2.2545, 2.2610, 2.2615 inches). Press is Forster Co-Ax.


without reading all posts IMO yes
in practice I have found that different neck tensions will cause different measurements

think about it if a bullet is harder to seat it will and does not seat to the same oal as one that slips in easy, the harder to seat projectile will leave a ring impression on the ogive, the difference may be a couple of thou, powder compression can make a difference as well
I have a force dial on my press that shows differing forces used to seat bullets in different cases that shows the different neck tension and oal
you have to understand that sizing brass or seating and pulling bullets can make the brass harder although when pulling a bullet you will make the neck looser as it has been stretched to the size of the bullet that had been seated
and when try to get your oal on a dummy by making small adjustments to the die will get that oal right but the next one you try at that setting will usually be different but only just so most people will make a dummy and use it for setting up the die but give a quarter turn more before seating

if you are seating close to the lands you will need consistency but if you jam or jump you wont have to be so uniform
you must also consider that bullet ogives do vary so it is beneficial to check and batch bullets for consistent oal's

I hope this helps :drinks:


Hi Marksman,

Yes it all helps. It sound like you are indicating there will be a difference but the difference I experienced for 2 of those rounds seems excessive (0.010) but another person on this thread seemed to indicate it may not be. It looks like I need to lubricate the necks to knock out any variance for pressure when pressing a bullet (other than dinged brass). And as mentioned earlier I was simply pushing the bullet in a bit at a time (never removing the bullet from the case) till I reached the desired measurement.

Another thing I should mention is that I do not in any way, shape or form want to seat 'Jam'ed. That scares the hell out of me because I see it as a potential area where pressure issues become much harder to control, ie. the jaming amount/measurement effects how much pressure produced so getting that exactyl right with measurements oal, neck tension is just too risky for my blood. I understand many comp shooters do it so it is doable, but not for me as a beginner on this journey.
cirles
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Re: Neck Tension issues? (different seating CBTO measurement

Post by Apollo » 12 May 2019, 3:58 pm

"cirles"

I have a couple of the Hornady Anvils, not sure if this still happens but Stuart Elliott used to modify them slightly by drilling a small part of the centre so that it provided a better surface in case there was a slight dimple in the middle of say a bullet that wouldn't sit properly. Probably doesn't matter much for general use. I also have a range of inserts and kit from Hornady for measuring bullets and cases. All handy when one is just checking or setting stuff up. However, a lot of this I don't use much any more. I know my measurements so checking a CBTO I do just use a Sinclair Nut to check seating each reloading session. I jam bullets generally 0.020" or there abouts since my neck tension is very low and closing the bolt does what is known as "soft seating" ie the bolt pushed the bullet onto the lands but really not much further.

I am not familiar with Forster Dies but somewhere in the info for your specific die it should mention something about the seating stem or alternatives. You could test the seating stem by say putting a small dob of something on the meplat to see if it bottoms out on the seating stem You should also not ever see a mark on the bullet ogive from the seating stem if all is correct unless for some reason the seating pressure is excessive. I use 130gr Berger VLD's as I found the 140gr were too heavy for my calibre to provide the accuracy I wanted, now Berger have shortened the length of the 130gr VLD and it doesn't work as accurate as it did in the past so I switched to Copperhead Bullets, however now Ken has a supply problem with J4 Jackets and is switching those to Sierra Jackets...so to see if they perform.

I was talking about removing the bullet and re-seating the bullet in the same case over and over without sizing the neck each time. Each time you insert the bullet it will open up the neck just that ever so slight amount.

You will have a good time shooting 500M Fly but I bet the bug bites when you have a good days shooting that you feel you can improve on so then you go chasing accuracy from what you have at hand or better.

I started with a .243W Tikka T3 shooting at home on my 500m target. It wasn't long before I started upgrading that and also converted it to a 65.x47L plus ordered a Custom built Long Range Target Rifle. The March Scopes I use cost as much if not far more than the rifles they are mounted on. My reloading gear and components I have would be around 10 grands worth. Farley and SEA Coaxial Front Rests and nearly bought a SEB but the dollars ran out.

Anyway, I love accurate shooting and probably go out about every second day to cull some varmints around home out to say 300 metres to make it easy. Target shooting at a number of distances I believe helps me in not only judging distance but understanding trajectory. General use here from day to day is a .223R Varmint Rifle (CZ527) or a Sako 85 .204Ruger.

Best of luck.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by Apollo » 12 May 2019, 4:31 pm

If this is what you have then you should be right as far as the seating stem goes... See description.

https://brtshooterssupply.com.au/produc ... r-die.html
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Re: Neck Tension issues? (different seating CBTO measurement

Post by cirles » 12 May 2019, 4:34 pm

Apollo,

Thanks for the clarification & suggestion on how to check if the seating stem is an issue, great idea.

It certainly is a hobby where you can spend plenty of dollars on equipment. Wish I had an area to go to (not club) to shoot longer range (1000 meter) but will tackle that in the future as know someone who deals with farmers, so seems the best avenue for pursuing that. I also do Pistol/Revolver metallic silhouette shooting (recently started) in 9mm currently but will progress to large calibre as have always wanted to shoot that ever since I shot a Freedom Arms 454 many, many years ago.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by cirles » 12 May 2019, 4:37 pm

Apollo wrote:If this is what you have then you should be right as far as the seating stem goes... See description.

https://brtshooterssupply.com.au/produc ... r-die.html


Yes that's it, thanks for confirming this, saves me having to try your suggestion :D
cirles
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Re: Neck Tension issues? (different seating CBTO measurement

Post by SCJ429 » 12 May 2019, 6:33 pm

You should do well with your Tikka, they have brilliant barrels on them for a factory unit. I have a Tikka in 223 which can shoot under an inch at 300 and under three inches at 500. You will find 500 metre shooting is quite a challenge and can be humbling when you cannot see what you are doing and the conditions keep changing.

To start out I would keep things simple and concentrate on making straight ammo with light neck tension. If you feel a pill seat with more pressure than usual, set it aside and use it for a sighter. Marksman mentioned that he has a strain gauge on his press so that he can observe this. Inconsistant neck tension is the biggest contributor to poor accuracy which is why guys go to such lengths as neck turning, use bushing dies and regular annealing.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by Apollo » 12 May 2019, 7:30 pm

To add a bit to this, being that I too believe consistent neck tension is vital to doing any reloading with accuracy in mind. Doesn't have to be for competition target shooting but trying to create the most accurate reloading within your own means.

Like Marksman, I too use a strain gauge to watch what is happening with seating bullets but over the years I have seated so many thousands of bullets I can pretty much feel when one is either too loose or too tight so they get marked with a felt pen. Since all my cases are sorted into increasing weight / capacity I don't throw a case unless next time it has the same problem. Using an Arbor press it's quite sensitive as to the force you exert on such a small lever as opposed to a large reloading press. This is what I use with a 0.0005" Dial Gauge...

http://brtshooterssupply.com.au/product ... -2016.html

Like I have said before, I anneal cases every reload with an Induction Annealer..

Mark I version of this .. http://brtshooterssupply.com.au/product ... -unit.html

Everyone is different in their circumstances and reasons for reloading plus some just cannot afford the gear they would like to use. Just enjoy what you can from the best you can make with your own equipment.
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Re: Neck Tension issues? (different seating CBTO measurement

Post by cirles » 12 May 2019, 10:22 pm

To SCJ428 & Apollo,

Thanks guys for your continuing suggestions & thoughts + experience on this reloading & shooting business, in certainly gives me more of an insight into what is involved when you take it too the next level. Annealing after every reload sounds expensive (disregarding initial equipment cost) just in electricity costs alone.

When I decided to buy a rifle & also to reload (mainly for keeping costs down), I never imagined setting up for accuracy would get so complicated. So certainly a learning experience here & I will just keep plugging away till am satisfied with what I can do. I am hoping that the urge to upgrade or acquire even more equipment in the service of more accuracy wont hit me in the future as this has proven to be a costly hobby so far just getting to this point (with admittedly good quality equipment & consumables).
cirles
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